Daily Archives: October 20, 2021

Perpetually thinking about “things”

Yep, I’m still thinking because I can’t “do” because my money is getting spent on other things, like buying windows I can actually see through, and health care. Yes, we are replacing the opaque thermal windows that have degraded so bad that one corner is almost like the insides were painted over. Also paying for seeing a doctor who is not the Lab Rat Keeper.

But that’s not what I was thinking about today. I was thinking about the frame, about how I can make it easier if I make it in bolt-together sections with bolt-in braces that keep the sections rigid, and allow for different suspensions for real A-B-A testing. Like I could build one front clip with the straight axle, and another front clip with independent front suspension, and swap back and forth between the two to get a true comparison. Like swap in a few hours from straight to wobbly.

But the first part will be building the roll cage with the two hoops that are exactly the same size as the body and barely clear it as the body passes through the halo opening in the top of the cage with the bolt-in brace removed. The thing is to route the bracing so that as little needs to be removed as possible to get the body inside after everything gets painted but still braces everything against torsional flexing. What I have is a full cross brace all the way from the left to the right but split to unbolt and allow the body to get through. Then the diagonals run from the corners to the transverse brace in the middle to where the brace is removed for the body to get through. There is not that much vertical thickness to the body so most of the opening can be blocked by the diagonal bracing and still allow the body to get fed through sideways from the top. Just spin the body through the roll axis and let it fall through the halo by overlapping the diagonal bracing.

Don’t forget I have to get through that hole to get in and out of the car. I have been thinking about that and the motions required, where I have to grab and brace my body. From inside getting out is easier than from the outside getting in. Getting out is a matter of bracing my feet against the transmission crossmember on the floor, grabbing the cross brace of the cage and using my legs to push me up against my arms and sitting on the top of the cage and swinging my legs over the side and sliding down until I’m standing outside the car. Getting in requires climbing until I can sit on the side of the cage and swinging my legs over the side and into the car and using the bracing to lower my body into the seat. Anyway I have to get two 12 foot sticks of roll cage material (the 1.5″ diameter 0.120″ wall) and get two legs bent at right angles 46.5″ apart, centered on the stick so I have lots of material to work with to set the height of the cage. The top part of the upper frame rail and diagonal braces are also part of the cage, so they have to be made from the same material. But the front clip can be made from 0.060″ wall tubing which saves a few more pounds.

And I didn’t get good sleep last night, so I’m nodding off at the keyboard. I’ve basically spelled out the changes in the new design, so I’ll put this post and me to bed.